Hermes AI Agent — VS Code Extension
VS Code sidebar for the Hermes CLI agent runtime. Streams chat, executes tools, manages sessions, and tracks context usage over the Agent Client Protocol (ACP).
Requires Hermes CLI installed and authenticated. The extension spawns hermes acp as a local subprocess — no cloud proxy, no hosted backend.
Features
Chat
- Sidebar panel with streaming markdown rendering (DOMPurify-sanitized)
- Extended thinking shown as gold status line
- Inline image rendering from Hermes
MEDIA:/path protocol
- Copy buttons on code blocks
- Tool calls displayed with kind labels (Read, Edit, Bash, Search, Fetch) and file paths
- Status:
✓ done, ⋯ running, ✗ error
- Edited files auto-open in VS Code; reads open as preview tabs
- Todo overlay from Hermes's todo tool
Skills
- Skills picker (
✦ button) loads from ~/.hermes/skills/
- Multi-select — injected as advisory prefix in the prompt
Slash Commands
Grouped command menu (/ button). Three dispatch modes: immediate execute, inline argument prompt, or confirmation dialog.
| Section |
Commands |
| Session |
/title, /new, /retry, /compact, /save |
| Info |
/context, /usage, /tools, /help |
| Config |
/yolo (auto-approve dangerous ops, red glow), /reasoning |
| Danger |
/reset (with confirmation) |
Slash command responses render as centered system messages, not conversation bubbles.
Context & Attachments
- Active file, selection, and open tabs sent automatically
- File attachment via
⊕ button, drag & drop, or Ctrl+V paste
- Files sent as path references — Hermes reads on demand
Sessions
- Persistent across VS Code reloads (stored in
workspaceState)
- Session picker: switch, create, rename, delete
- Auto-titled from first user message
- ACP session ID stored for context resume
Models
- Anthropic Claude + OpenAI Codex in grouped picker
- Switch via header dropdown or
/model provider:model-id
- Dynamic catalog from
~/.hermes/models_dev_cache.json
Token Tracking
- Context usage displayed as
Xk / 1M with progress bar
- Color warnings at 70% (gold) and 90% (red)
Queue & Interrupt
- Send follow-ups while busy (queued)
- New messages cancel the current turn
- Gold glow on composer while agent is working
Requirements
- Hermes CLI installed (
pip install hermes-agent)
- Hermes authenticated (
hermes setup)
- VS Code 1.85+
- Remote SSH: runs on the workspace/server side (
extensionKind: ["workspace"])
Getting Started
pip install hermes-agent && hermes setup- Install extension from Marketplace or
.vsix
- Open Hermes panel from the activity bar
- Send a message
Settings
| Setting |
Default |
Description |
hermes.path |
hermes |
Path to the Hermes binary (machine scope) |
hermes.debugLogs |
false |
ACP diagnostic logs in the Output channel |
Architecture
Extension Host (Node.js)
├── extension.ts — activation, wiring
├── acpClient.ts — JSON-RPC 2.0 over stdio
├── sessionManager.ts — ACP session lifecycle, streaming dedup
├── sessionStore.ts — workspaceState persistence
├── chatPanel.ts — WebviewViewProvider, message dispatch
├── htmlTemplate.ts — HTML/CSS builder
├── protocol.ts — typed ACP parsing
├── types.ts — shared type definitions
├── modelCatalog.ts — model menu loader
└── skillCatalog.ts — skill directory loader
Webview (sandboxed)
├── main.ts — event handlers, send logic
├── state.ts — state factory
├── renderers.ts — markdown, messages, todo overlay
└── menus.ts — dropdowns, status bar
Communication: JSON-RPC 2.0 over stdio to hermes acp subprocess. Webview sandboxed with CSP + DOMPurify. Media isolated to extension storage.
Credits
License
MIT
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